Flash MX 2004 Games : Art to ActionScript

Flash MX 2004 Games
//Functionality is control inside the Rhino Movie Clip
//The variable ’wrongcount’ is update everytime the child
//enters an incorrect value. This is handled using the ’enterData’ loop
//When the child presses the return key the Clip jumps to
//’validateData’. A correct answer jumps to ’correct’
//An incorrect answer and the Clip jumps to ’inCorrect’
//where the variable ’wrongcount’ is incremented. If ’wrongcount’
//is equal to one then the clip jumps to ’showAnswer’
//where the correct answer is displayed for the child.
//Then the game moves on to the next problem by calling ’nextProblem’.
Believe me, if you do that you will feel a warm glow when you return to your own code, and
other developers who read your code will think just one thing – respect!
One final tip: don’t change a variable’s value outside the current scope. If you find that you
do need to change the value of a variable in several places then set the variable’s value using a
function, such as
function setMyVariable(newValue, calledFrom){
trace("setMyVariable to " + newValue + " called from " + calledFrom);
myVariable = newValue;
}
This will make tracking down any errors much easier. The ‘trace’ will show you who attempted
to change the value of the variable. Often you can find that as you develop your programs there
may be errant code that is left over from an earlier incarnation of the program and that this errant
code is setting the values in a movie clip inappropriately. These type of errors are much easier to
find if you follow the simple rule ‘don’t change the value of a variable directly outside the current
scope. Always use a function call that says who was trying to change the value.’
Creating a new object
Object-oriented programming involves combining the data and the operations on the data within
a single object. Flash allows you to create such an object. In this code snippet we create a new
object by calling the ‘point’ function. This type of function is sometimes called a constructor.
Inside the function variables are created and initialized. The variables ‘x’ and ‘y’ are both set to
zero, but the variables ‘init’ and ‘sum’ are set to point to functions. We can use the functions
from within the object. In this example ‘pt1’ calls the ‘init’ method which sets the values of ‘x’
and ‘y’ to 3 and 10 respectively and ‘pt2’ uses the same method to initialize the values. Then the
function ‘pt2’ uses the method ‘sum’ to add the point ‘pt1’ to its own internal data. After running
the program the output window will display 23 40.
1 pt1 = new point();
2 pt2 = new point();
3 pt1.init(3, 10);
144